In the power generation industry, as well understood by those skilled in the art, a power generator has a generator rotor and a generator stator. The generator rotor includes several rotor slots. The rotor slots conventionally have a plurality of electrically-conductive rotor wedges which hold the slot contents, e.g., coils, slot filler, within the slots. The slot contents should remain tight to prevent relative motion of the copper windings during slow roll operations which could result in wear of the windings and conductive particle creation, e.g., copper dusting. A tight slot contents also ensures the provision of adequate contact pressure on a damper system of the rotor, e.g., a wedge and rotor tooth, at low speeds to conduct currents generated with static start operation. The tightening of the slot contents is even further problematic between rotor slot wedges.
A conventional method for tightening the slot is to use a brute force technique which can be labor intensive. In this conventional method, all of the slots are gauged along the length. Slot fillers are then sanded to fit, and wedges are driven into the slot with a large hydraulic ram. The filler thickness under a given wedge is chosen by trial and error. If the filler is sanded too thin, the slot will be loose. If the filler is too thick, galling can occur when the wedge is driven into the slot. Tolerances between "too thin" and "too thick" can be too great and cause problems for the rotor. This method also allows the slot to loosen as the machine ages and insulation components creep with time.
Systems, such as shown in U.S. Pat. No. 5,430,340 by Shih et al. titled "Harmonic Current Path Spring Device Between Retaining Ring And Rotor Wedge Of A Dynamoelectric Generator," have been developed which use a spring below rotor slot wedges to bias the wedges against overlapping retaining rings. Such systems, however, fail to adequately address some of the above described problems and particularly the problem with loose contents between wedges.
Other systems have been developed, such as shown in U.S. Pat. No. 5,550,417 by Morrison et al. titled "Amortisseur Winding Arrangement, In A Rotor For Electrical, Rotating Equipment," which attempt to solve the problem of loose slot contents between wedges by physically and electrically connecting the wedges. Such a system uses arcuate linking members or inserts which are spring loaded to assist in retaining the wedges. The physical connection of the wedges and the custom forming of the wedges, however, are often not desirable.